JP2022156771A - Filter for capturing fine particle, and method for manufacturing filter for capturing fine particle - Google Patents

Abstract

To provide a filter for capturing fine particles having such a configuration as to be manufactured using a laser processing technique.SOLUTION: A filter for capturing fine particles has a transparent body having a first surface and a second surface and a thickness of 50 μm or more, and a plurality of through holes penetrating to the second surface from the first surface of the body, wherein when a position with a depth of 10 μm from the second surface is defined as a reference depth DS, in each of the through holes, a minimum cross section dimension at the reference depth DS is represented by φP, and a minimum cross section dimension between the reference depth DS and the second surface is represented by φP, φQ≤0.6 μm and φQ/φP≤0.5, are satisfied in the filter for capturing fine particles.SELECTED DRAWING: Figure 2

Description

The present invention relates to a particulate filter.

There is a need in many fields, such as medical facilities, pharmaceutical manufacturing plants, and high-cleanliness clean rooms, for fine particle trapping filters that can appropriately trap foreign substances contained in solutions.

International Publication No. WO2010/087483

As one configuration example of a filter for capturing fine particles, a system in which minute through holes are provided in part of the solution flow path of the filter and fine particles are captured in the through holes is conceivable.

In addition, it is conceivable to use a laser processing technique when mass-producing such a filter for trapping fine particles. This is because the laser processing technology can rapidly form a large number of through-holes with high dimensional accuracy in an object to be processed (for example, Patent Document 1).

However, in order to reliably trap fine particles, the fine particle trapping filter needs to have extremely fine through holes (fine through holes) of about 0.6 μm or less, for example. However, in general, laser processing technology limits the diameter of a hole formed in an object having a thickness of 50 μm or more to about 2 μm. For this reason, it is not easy to form the above-mentioned through-holes for trapping fine particles with high accuracy.

In particular, in a fine particle trapping filter, for example, it may be necessary to form a large number of 1,000 or more through-holes in an inspection area of 1 mm×1 mm. However, it is extremely difficult to form a large number of through-holes with a diameter of less than 2 μm in such a minute inspection area using a laser processing technique.

Due to this background, almost no example of manufacturing a particulate filter using laser processing technology has been found so far. However, it would be preferable in terms of quality and manufacturing cost if a fine particle trapping filter could be manufactured using a laser processing technique.

The present invention has been made in view of such a background, and an object of the present invention is to provide a fine particle trapping filter having a configuration that can be manufactured using laser processing technology. Another object of the present invention is to provide a method for manufacturing such a particulate filter.

In the present invention, a filter for trapping fine particles,
a transparent body having a first surface and a second surface and having a thickness of 50 μm or more;
a plurality of through holes penetrating from the first surface to the second surface of the body;
has
A _position with a depth of 10 μm from the second surface is defined as a reference depth DS,
In each through-hole, when the minimum cross-sectional dimension at the reference depth D _S ) is φ _P and the minimum cross-sectional dimension between the reference depth D _S and the second surface is φ _Q ,
A particulate trapping filter is provided wherein φ _Q ≦0.6 μm and φ _Q /φ _P ≦0.5.

Further, in the present invention, there is provided a method for manufacturing a particulate filter, comprising:
(I) providing a transparent substrate having first and second surfaces facing each other;
(II) irradiating the first surface of the substrate with a laser beam to form a plurality of substrate through-holes penetrating the substrate from the first surface to the second surface;
(III) placing a coating layer on the second surface of the substrate to form a plurality of through-holes penetrating the substrate and the coating layer;
A manufacturing method is provided, comprising:

INDUSTRIAL APPLICABILITY In the present invention, it is possible to provide a fine particle trapping filter having a configuration that can be manufactured using laser processing technology. Another object of the present invention is to provide a method for manufacturing such a particulate filter.

1 is a top view schematically showing a particulate trapping filter according to an embodiment of the present invention; FIG. FIG. 2 is a diagram schematically showing an example of a cross section of an inspection region of the particulate trapping filter according to the embodiment of the present invention shown in FIG. 1; FIG. 4 is a diagram schematically showing another cross section of a substrate through-hole in the substrate; 1 is a diagram schematically showing an example flow of a method for manufacturing a particulate filter according to an embodiment of the present invention; FIG. FIG. 2 is a diagram schematically showing one step of a method for manufacturing a particulate trapping filter according to one embodiment of the present invention; FIG. 2 is a diagram schematically showing one step of a method for manufacturing a particulate trapping filter according to one embodiment of the present invention; FIG. 2 is a diagram schematically showing one step of a method for manufacturing a particulate trapping filter according to one embodiment of the present invention; FIG. 2 is a diagram schematically showing one step of a method for manufacturing a particulate trapping filter according to one embodiment of the present invention; 4 is a photograph showing an example of a cross-section of a through-hole formed in a sample according to an example; FIG. 11 is a photograph showing an example of a cross section of a through hole formed in a sample according to another example; FIG. FIG. 11 is a photograph showing an example of a cross section of a through hole formed in a sample according to still another example; FIG.

An embodiment of the present invention will be described below.

In one embodiment of the present invention, a filter for trapping particulates,
a transparent body having a first surface and a second surface and having a thickness of 50 μm or more;
a plurality of through holes penetrating from the first surface to the second surface of the body;
has
A _position with a depth of 10 μm from the second surface is defined as a reference depth DS,
In each through-hole, when the minimum cross-sectional dimension at the reference depth D _S ) is φ _P and the minimum cross-sectional dimension between the reference depth D _S and the second surface is φ _Q ,
A particulate trapping filter is provided wherein φ _Q ≦0.6 μm and φ _Q /φ _P ≦0.5.

As described above, in laser processing technology, the diameter of a hole formed in an object having a thickness of 50 μm or more is limited to about 2 μm, and it is not easy to form finer holes with high precision. In particular, it is extremely difficult to form a large number of through-holes with a diameter of less than 2 μm in a minute inspection area by laser processing technology.

In this respect, the particulate filter according to one embodiment of the present invention has the configuration as described above. As will be described in detail later, the fine particle trapping filter having such a structure has a thickness of 50 μm or more and can be manufactured using a laser processing technique.

Accordingly, in one embodiment of the present invention, a particulate filter can be manufactured with high quality and low manufacturing cost.

(Filter for capturing fine particles according to one embodiment of the present invention)
An embodiment of the present invention will be described in more detail below with reference to the drawings.

1 and 2 schematically show one configuration example of a fine particle trapping filter according to one embodiment of the present invention. FIG. 1 shows a top view of a particulate trapping filter (hereinafter referred to as "first filter") according to one embodiment of the present invention.

As shown in FIG. 1, first filter 100 has a transparent body 110 . Body 110 has a first surface 112 and a second surface 114 . An inspection region 120 is arranged on the body 110 .

In the example shown in FIG. 1, the first filter 100 has a substantially circular shape when viewed from above. However, the shape of the first filter 100 is not particularly limited, and may be, for example, an ellipse, a triangle, a quadrangle, or a polygon with pentagons or more.

In addition, in the example shown in FIG. 1, the inspection area 120 is arranged in a substantially square shape substantially in the center of the main body 110 when viewed from above. However, this is just one example. Inspection region 120 may be located in a non-central portion of body 110 . The inspection areas 120 may also be arranged in a non-square shape, such as a circular shape, an elliptical shape, a rectangular shape, or a polygonal shape with pentagons or more.

Also, the number of inspection areas 120 is not necessarily limited to one, and the inspection areas 120 may be provided at a plurality of locations on the main body 110 .

Furthermore, in FIG. 1, the inspection area 120 is clearly represented by a rectangular frame. However, it should be noted that in the first filter 100, it is often the case that the boundary between the inspection area 120 and the non-inspection area cannot be clearly identified visually.

A portion of the inspection area 120 is shown enlarged in the left circular frame of FIG. As shown in this frame, a large number of through holes 122 are formed in the inspection area 120 .

The density of the through-holes 122 in the inspection area 120 is not particularly limited, but is, for example, 100/mm ² or more.

The form of the two-dimensional array of through-holes 122 is not particularly limited. The through-holes 122 may be arranged regularly or randomly.

Moreover, when the through-holes 122 are arranged regularly, the manner of arrangement, the pitch, and the like are not particularly limited. For example, as shown in FIG. 1, the through holes 122 may be regularly arranged vertically and horizontally. The pitch may range, for example, from 10 μm to 100 μm.

FIG. 2 schematically shows an example of a cross section of the inspection area 120 of the main body 110. As shown in FIG. FIG. 2 shows a cross section along the central longitudinal axis of the plurality of through holes 122 .

As shown in FIG. 2, the main body 110 has a substrate 140 and a coating layer 150 formed on one surface of the substrate 140 . The first surface 112 of the body 110 corresponds to the surface of the substrate 140 on which the coating layer 150 is not applied, and the second surface 114 corresponds to the surface of the coating layer.

In FIG. 2, dashed line D _i represents the boundary between substrate 140 and coating layer 150 . However, in practice, this boundary D _i may often be unclear.

Body 110 includes a number of through holes 122 . Each through-hole 122 has a first opening 125 on the first surface 112 side of the body 110 and a second opening 127 on the second surface 114 .

Each through-hole 122 is formed by penetrating both the substrate 140 and the coating layer 150 . Therefore, the first opening 125 of the through-hole 122 is an opening on the substrate 140 side, and the second opening 127 is an opening on the coating layer 150 side.

In each through-hole 122, the portion on the base material 140 side is particularly referred to as "base material through-hole 132a", and the portion on the coating layer 150 side is referred to as "coating layer through-hole 132b".

In the example shown in FIG. 2, in each through hole 122, the base through hole 132a has a tapered shape, and the "minimum cross-sectional dimension" monotonically decreases from the first opening 125 to the boundary _Di.

Here, the “minimum cross-sectional dimension (of the through hole)” means the smallest distance between opposing side walls in a cross section passing through the longitudinal central axis of the through hole 122 . Therefore, if the cross-section of the through-hole is circular, the "minimum cross-sectional dimension" represents the diameter, and if it is elliptical, the "minimum cross-sectional dimension" represents the minor axis dimension.

Moreover, precisely, the first opening 125 and the second opening 127 are not "through-hole cross sections". However, the present application also uses the term "minimum cross-sectional dimension" when describing the dimensions of these openings 125,127.

In the example shown in FIG. 2, the taper angle .theta. Here, the taper angle θ of the substrate through-hole 132a is represented by the angle between the normal line of the first surface 112 and the side wall of the substrate through-hole 132a.

Referring to FIG. 2 again, coating layer through-holes 132b of through-holes 122 have a more complex cross-sectional shape than substrate through-holes 132a.

For example, in the example shown in FIG. 2, the coating layer through-hole 132b extends from the boundary D _i to the second surface 114 (but not including the boundary D _i ) at the constriction 154 with the smallest minimum cross-sectional dimension. has a cross-sectional shape with That is, when the minimum cross-sectional dimension of the narrowed portion 154 is φ _Q , φ _Q represents the smallest minimum cross-sectional dimension between the through holes 122 .

Here, in each through-hole 122, the position at a depth of 10 μm from the second surface 114 of the main body 110 is called a “reference depth” and is _denoted by DS. As shown in FIG. 2, reference depth D _s is located further from second surface 114 of body 110 than boundary D _i . Also, φ _P represents the minimum cross-sectional dimension of the through-hole 122 at the reference depth D _S .

In the first filter 100, when using the minimum cross-sectional dimensions φ _P and φ _Q defined above, each through-hole 122 satisfies φ _Q ≦0.6 μm and φ _Q /φ _P ≦0.5.
is characterized by satisfying

In particular, φ _Q /φ _P ≤ 0.4.

The first filter 100 has a narrowed portion 154 that satisfies the minimum cross-sectional dimension φ _Q ≦0.6 μm, which is difficult to form by a general laser processing method. ).

Therefore, the first filter 100 can be used, for example, as a filter that captures fine particles with particle diameters exceeding about 0.6 μm.

Also, in the first filter 100, the portion of the substrate through-hole 132a can be formed using a general laser processing technique. The laser processing technology can form the substrate through-holes 132a having the same shape with high accuracy. Therefore, the first filter 100 can be manufactured with high quality and low cost.

Furthermore, in the first filter 100, the depth position of the constricted portion 154 in each through-hole 122 is any point from the second surface 114 to the boundary D _i (excluding the position of the boundary D _i ). can be aligned. In this case, it becomes possible to trap particles at substantially the same depth position in any of the through holes 122, which facilitates the detection of particles.

(Each portion of the particulate trapping filter according to one embodiment of the present invention)
Next, each portion of the particulate trapping filter according to one embodiment of the present invention will be described in more detail.

For the sake of clarity, each part of the particulate trapping filter according to the embodiment of the present invention will be described by taking the above-described first filter 100 as an example. Accordingly, the reference numerals shown in FIGS. 1 and 2 are used when representing each part.

(Body 110)
In the example shown in FIG. 1, the main body 110 has a substantially circular shape when viewed from above. However, the shape of the main body 110) is not particularly limited, and may be, for example, an ellipse, a triangle, a quadrangle, or a polygon with pentagons or more.

Body 110 is constructed of a transparent material. Here, "transparent" means having an average transmittance of 80% or more at wavelengths of 360 nm to 830 nm.

Therefore, when the first filter 100 is used, particles can be detected by common optical techniques such as infrared spectroscopy, Raman spectroscopy, optical microscopy, and fluorescence microscopy.

The thickness of the main body 110 is 50 μm or more, preferably 60 μm or more. There is no particular upper limit for the thickness of the main body 110, but the thickness of the main body 110 may be, for example, 1 mm or less.

When the minimum cross-sectional dimension of the _first opening 125 of the main body 110 is φ1, φ1 preferably satisfies _{5 μm≦φ 1 ≦} 50 μm.

Further, when the minimum cross-sectional dimension of the _{second opening 127 of the main body 110 is φ2, φ1 preferably satisfies 0.2 μm≦φ 2 ≦ 5} μm.

Also, the minimum cross-sectional dimension φ _Q of the constricted portion 154 is preferably 0.2 μm or more.

As described above, it is difficult to form a through-hole having a minimum cross-sectional dimension of 0.6 μm or less only by laser processing technology.

However, body 110 has substrate 140 and coating layer 150 . Therefore, in the first filter 100, the main body 110 can be formed with the through hole 122 having the narrowed portion 154 with the minimum cross-sectional dimension _φQ of 0.6 μm or less.

The constriction 154 may exist in a range of 0≦d<5 μm, where d is the depth of the constriction 154 from the second surface 114 . Note that the constriction 154 may be on the second surface 114, but at a different location than the boundary _Di.

Through-holes 122 are preferably formed in inspection region 120 of main body 110 at a density of 100/mm ² or more. More preferably, the density of through-holes 122 is in the range of 500/mm ² to 15,000/mm ² .

(Base material 140)
The type of base material 140 forming part of main body 110 is not particularly limited. Substrate 140 may be composed of, for example, a transparent material such as glass or resin.

The thickness of the base material 140 is preferably 50 μm or more. Also, the thickness of the base material 140 may be, for example, 1 mm or less.

Note that the cross-sectional shape of the substrate through-hole 132a shown in FIG. 2 is merely an example, and the substrate through-hole 132a may have a different cross section. For example, the substrate through-hole 132a may have a cross-sectional shape as shown in FIG.

FIG. 3 schematically shows another cross section of the substrate through-hole 132a. Note that FIG. 3 shows only the base material 140 portion of the main body 110 and does not show the coating layer 150 .

As shown in FIG. 3 , this substrate through-hole 132 a has a substrate constriction portion 148 inside the substrate 140 . Substrate through-hole 132 a has a shape such that the “minimum cross-sectional dimension” increases from this substrate constriction 148 toward each surface of substrate 140 .

The substrate through-hole 132a having such a cross-sectional shape is likely to be formed when the substrate 140 having fine through-holes is wet-etched, as will be described later.

Thus, in one embodiment of the present invention, it should be noted that the cross-sectional shape of the substrate through-hole 132a is not particularly limited.

(Coating layer 150)
The type of coating layer 150 is not particularly limited as long as it is transparent.

The material of the coating layer 150 is not particularly limited as long as it is transparent, but materials mainly composed of silica, alumina, magnesium oxide, and magnesium fluoride are preferable because they have a low refractive index and can maintain a high transmittance. In addition, materials mainly composed of silica, hafnium oxide, tantalum oxide, and magnesium fluoride are preferable because they have a small extinction coefficient in the ultraviolet region.

The coating layer 150 is preferably composed of silica or magnesium fluoride, in particular, because it has a low refractive index and a low extinction coefficient over a wide wavelength range.

The thickness of the coating layer 150 is not particularly limited, but preferably ranges from 0.1 μm to 5 μm, for example.

The thickness of the coating layer is 10 μm or less at maximum. Therefore, the depth from the second surface 114 of the body 110 to the boundary D _i is equal to or less than the distance from the second surface 114 to the reference depth D _s .

An embodiment of the present invention has been described above using the first filter 100 as an example.

However, the above description is merely an example, and a particulate filter according to an embodiment of the invention may have other forms.

For example, in the example shown in FIG. 2, the coating layer through-holes 132b of the first filter 100 gradually increase in minimum cross-sectional dimension from the constriction 154 toward the second surface 114. As shown in FIG. Alternatively, however, the coating layer through-holes 132b may have a morphology that gradually decreases in minimum cross-sectional dimension from the boundary D _i toward the second surface 114 . In that case, the minimum cross-sectional dimension of the second opening 127 is _φQ .

Also, for example, the coating layer through-hole 132b may partially have a straight portion extending parallel to the thickness direction of the coating layer.

That is, in the particulate filter according to one embodiment of the present invention, the substrate through-holes 132a and the coating layer through-holes 132b may have any shape as long as they have the characteristics described above.

Furthermore, in the above description, the fine particle trapping filter according to one embodiment of the present invention has been described by taking as an example the case where the transparent main body is formed with the through holes. However, the particulate trapping filter according to one embodiment of the present invention may have slits instead of through holes.

(Manufacturing method of particulate trapping filter according to one embodiment of the present invention)
Next, with reference to FIGS. 4 to 8, an example of a method for manufacturing a particulate trapping filter according to an embodiment of the present invention will be described.

FIG. 4 schematically shows a flow of a method for manufacturing a particulate filter according to one embodiment of the present invention (hereinafter referred to as "first method").

As shown in FIG. 4, the first method consists of:
(1) providing a transparent substrate having first and second surfaces facing each other (step S110);
(2) A step of irradiating the first surface of the substrate with a laser beam to form a plurality of substrate through-holes penetrating the substrate from the first surface to the second surface (step S120) and
(3) placing a coating layer on the second surface of the base material to form a plurality of through-holes penetrating the base material and the coating layer (step S130);
have

Each step will be described below with reference to FIGS. 5 to 8 as well. Here, as a filter for trapping fine particles, the first filter shown in FIGS. 1 and 2 will be described as an example of the manufacturing method thereof. Therefore, the reference numerals shown in FIGS. 1 and 2 are used when referring to each portion of the particulate filter.

(Step S110)
First, a transparent substrate 140 is prepared.

FIG. 5 shows a perspective view of substrate 140 . Substrate 140 has a first surface 142 and a second surface 144 .

Note that in the example shown in FIG. 5, the first surface 142 and the second surface 144 have substantially circular shapes. However, the shapes of first surface 142 and second surface 144 are not particularly limited. The first surface 142 and the second surface 144 may have shapes such as, for example, ellipses, triangles, rectangles, or polygons with pentagons or more.

Substrate 140 may be composed of any material as long as it is transparent. The substrate 140 may be made of glass or resin, for example.

The thickness of the base material 140 is preferably 50 μm or more.

Note that an absorbent may be placed on the first surface 142 of the substrate 140 before the next step S120. When the absorbing material is installed, the energy of the laser beam with which the base material 140 is irradiated can be absorbed more efficiently. Therefore, in the next step S120, laser processing can be performed with lower energy and high quality.

However, installation of the absorbing material 220 is optional.

FIG. 6 schematically shows a state in which the absorbent material 220 is placed on the first surface 142 of the base material 140 .

The material of the absorption layer 220 is not particularly limited as long as it has a function of absorbing at least part of the energy of the pulse laser used. The absorbing layer 110 may be, for example, a synthetic resin ink or a pigment containing carbon black.

(Step S120)
Next, a laser beam is irradiated from the first surface 142 side of the substrate 140 to form the substrate through-holes 132a.

Although the type of laser light is not particularly limited, UV laser is preferable.

The laser light may be, for example, a short pulse laser.

FIG. 7 schematically shows a cross section of the base material 140 in which the base material through-holes 132a are formed. Note that the absorbent 220 is omitted in FIG.

A plurality of substrate through-holes 132 a extending from the first surface 142 to the second surface 144 are formed in the substrate 140 by the laser beam irradiation.

As shown in FIG. 7, the substrate through-hole 132a formed by laser beam irradiation tends to have a shape in which the cross section is tapered from the first surface 142 toward the second surface 144. As shown in FIG.

The taper angle θ ₁ ranges, for example, from 65° to 89°.

Each substrate through-hole 132 a has a first opening 226 a in the first surface 142 of the substrate 140 and a second opening 226 b in the second surface 144 .

The minimum cross-sectional dimension of the first opening 226a is, for example, in the range of 4 μm to 30 μm, preferably in the range of 4 μm to 15 μm.

Also, the minimum cross-sectional dimension of the second opening 226b is, for example, in the range of 2 μm to 10 μm, preferably in the range of 2 μm to 5 μm.

The number of substrate through-holes 132a to be formed is not particularly limited. When used in a filter for capturing fine particles, the density of the substrate through-holes 132a is, for example, 100/mm ² or more, preferably in the range of 500/mm ² to 15,000/mm ² . .

The substrate 140 may be wet-etched after the substrate through-holes 132a are formed.

By performing wet etching, the absorbent 220 and debris generated during laser processing can be removed.

For example, if the substrate 140 is glass, the wet etching process may be performed in a hydrofluoric acid solution.

It should be noted that the shape of the substrate through-hole 132a may often change when the wet etching process is performed. For example, the first opening 226a of the substrate through-hole 132a can vary from 4.1 μm to 30.1 μm. Also, the minimum cross-sectional dimension of the second opening 226b can vary, for example, from 2.1 μm to 10.1 μm.

Further, the shape of the cross section of the substrate through-hole 132a can be roughly divided into two modes.

In the _first mode, the cross-sectional dimension of the substrate through-hole 132a is expanded while the taper angle θ1 is maintained.

In the second mode, a cross-sectional shape as shown in FIG. 3 is obtained. In other words, the substrate through-hole 132 a is shaped to have a substrate constricted portion 148 between the first surface 142 and the second surface 144 .

A cross-sectional configuration such as that shown in FIG. 3 is likely to occur when the substrate 140 is thick and/or when the dimensions of the first opening 226a and the second opening 226b are small.

That is, when the dimensions of the first opening 226a and the second opening 226b are small, it becomes difficult for the etching solution to sufficiently permeate the inside of the substrate through-hole 132a. In that case, portions near both surfaces 142 and 144 of the substrate through-hole 132a are selectively etched to form the substrate through-hole 132a having the substrate constricted portion 148 as shown in FIG.

The same is true when the base material 140 is thick.

Thus, the shape of the substrate through-hole 132a can change before and after the wet etching process. However, in the present application, the substrate through-holes 132a after the wet etching process are referred to as "substrate through-holes 132a" as they are.

Moreover, when the first surface 142 and the second surface 144 of the substrate 140 are etched by wet etching, different surfaces (new surfaces) are exposed.

However, the amount of etching of first surface 142 and second surface 144 of substrate 140 is minor. Therefore, after the wet etching process, the respective exposed surfaces of substrate 140 are still referred to herein as "first surface 142" and "second surface 144."

(Step S130)
A coating layer is then applied to the second surface 144 of the substrate 140 .

This step is performed to adjust the size and shape of the tip of the substrate through-hole 132a.

A method for installing the coating layer is not particularly limited.

The coating layer may be deposited on the second surface 144 of the substrate 140 by, for example, sputtering or vapor deposition.

The sputtering method or vapor deposition method can significantly reduce the possibility that the substrate through-holes 132a are blocked, and can appropriately form a coating layer having the coating layer through-holes 132b communicating with the substrate through-holes 132a. .

As described above, the type of coating layer is not particularly limited. _The coating layer may be composed of, for example, silica, alumina, MgO, MgF, _Ta2O5 , or the like.

The thickness of the coating layer is at most 10 μm or less, for example in the range of 0.1 μm to 5 μm.

FIG. 8 schematically shows a state after the coating layer 150 is applied to the second surface 144 of the base material 140 . In FIG. 8, dashed line L1 represents the boundary between substrate 140 and coating layer 150, that is, _Di. However, the boundary D _i can often be difficult to discern under optical and electron microscopy.

As shown in FIG. 8, the coating layer 150 is formed to have a coating layer through-hole 132b corresponding to each substrate through-hole 132a. In other words, the coating layer through-holes 132 b of the coating layer 150 are formed to extend the substrate through-holes 132 a formed in the substrate 140 to the surface 152 of the coating layer 150 .

Thereby, a through-hole 122 can be formed that penetrates from the first surface 142 of the substrate 140 to the surface 152 of the coating layer 150 .

The through hole 122 has a third opening 240c on the surface 152 side of the coating layer 150 .

The minimum cross-sectional dimension φ ₂ of the third opening 240c ranges from 0.2 μm to 5 μm.

Thus, the first method may form a plurality of through-holes 122 extending from the first surface 142 of the substrate 140 to the surface 152 of the coating layer 150 .

These through-holes 122, using the minimum cross-sectional dimensions φ _P and φ _Q defined above, are:
φ _Q ≤ 0.6 µm, and φ _Q /φ _P ≤ 0.5
meet.

Here, φ _P is the minimum cross-sectional dimension of the through-hole 122 at the reference depth Ds (not shown in FIG. 8).

Further, the position where the minimum cross-sectional dimension _φQ is obtained in the through-hole 122 may be the third opening 240c portion. In this case, φ ₂ =φ _Q.

In the first method, a narrowed portion 154 that satisfies the minimum cross-sectional dimension φ _Q ≦0.6 μm, which is difficult to form by a general laser processing method, is formed inside each through-hole 122 (or on the surface 152 of the coating layer 150). ).

Therefore, the filter manufactured by the first method can be used, for example, as a filter that captures fine particles with particle diameters exceeding about 0.6 μm.

Also, in the first method, the portion of the substrate through-hole 132a can be formed using a general laser processing technique. Therefore, according to the first method, a fine particle trapping filter can be manufactured with high quality and low cost.

Furthermore, in the first method, in each through-hole 122, the depth position of the narrowed portion 154 is set to any point from the surface 152 of the coating layer 150 to the boundary D _i (excluding the position of the boundary D _i ). can be aligned. In this case, it becomes possible to trap particles at substantially the same depth position in any of the through holes 122, which facilitates the detection of particles.

Next, examples of the present invention will be described. In the following description, Examples 1 to 3 are working examples, and Example 11 is a comparative example.

(Example 1)
An evaluation sample was produced by the following method.

First, a substrate having a first surface and a second surface facing each other was prepared. A glass substrate having a thickness of 200 μm was used as the base material.

Next, a plurality of through-holes (substrate through-holes) were formed by irradiating the first surface side of the substrate with a laser beam. A pulse wave laser was used as the laser light.

Next, a coating layer was formed on the second surface of the substrate by a sputtering method. The coating layer was a silica layer with a thickness of 3.1 μm. After deposition, through-holes were obtained that penetrated from the substrate to the coating layer.

Thus, an evaluation sample (hereinafter referred to as "sample 1") was produced.

In the through-holes of Sample 1, the minimum cross-sectional dimension φ ₁ of the first opening on the side of the substrate and the minimum cross-sectional dimension φ ₂ of the second opening on the side of the coating were measured. As a result, φ ₁ =8.0 μm and φ ₂ =3.4 μm.

(Example 2)
A sample for evaluation was prepared in the same manner as in Example 1. However, in Example 2, the thickness of the coating layer was set to 4.3 μm.

The produced evaluation sample is called "Sample 2".

In the through-holes of Sample 2, the minimum cross-sectional dimension φ ₁ of the first opening on the side of the substrate and the minimum cross-sectional dimension φ ₂ of the second opening on the side of the coating were measured. As a result, φ ₁ =8.0 μm and φ ₂ =2.7 μm.

(Example 3)
A sample for evaluation was prepared in the same manner as in Example 1. However, in Example 3, the thickness of the coating layer was set to 4.9 μm.

The produced evaluation sample is called "Sample 3".

In the through-holes of sample 3, the minimum cross-sectional dimension φ ₁ of the first opening on the side of the substrate and the minimum cross-sectional dimension φ ₂ of the second opening on the side of the coating were measured. As a result, φ ₁ =8.0 μm and φ ₂ =2.8 μm.

(Example 11)
A substrate through-hole was formed in a glass substrate by the same method as in Example 1, and this was used as an evaluation sample. That is, in Example 11, no silica layer coating was performed.

The obtained sample for evaluation is called "Sample 11".

In the through-holes of sample 11, the minimum cross-sectional dimension φ ₁ of the first opening on the side of the substrate and the minimum cross-sectional dimension φ ₂ of the second opening on the side of the coating were measured. As a result, φ ₁ =8.0 μm and φ ₂ =2.0 μm.

Table 1 below summarizes the manufacturing conditions for each sample.

（断面評価）
作製された各サンプルを、いくつかの貫通孔の長手中心軸を通る断面で切断し、評価用試料を作製した。また、評価用試料を用いて、以下の寸法を測定した：
基準深さＤ_Ｓ（コーティング層の表面から１０μｍの位置）における貫通孔の最小断面寸法φ_Ｐ、および
貫通孔の狭窄部における最小断面寸法φ_Ｑ。

(Cross section evaluation)
Each of the prepared samples was cut along a cross section passing through the longitudinal central axes of several through holes to prepare samples for evaluation. Also, the following dimensions were measured using the evaluation sample:
The minimum cross-sectional dimension φ _P of the through-hole at the reference depth D _S (10 μm from the surface of the coating layer), and the minimum cross-sectional dimension φ _Q at the narrowed portion of the through-hole.

Here, the narrowed portion is defined as the depth position where the minimum cross-sectional dimension of the through hole is the smallest.

Except for sample 11, the position of the constriction was inside the coating layer. On the other hand, in sample 11, the constriction was the second surface of the substrate.

9 to 11 show examples of cross sections of the through-holes on the coating layer side in samples 1 to 3, respectively.

9 to 11, it is due to the reflection of light that some parts look whitish, and it should be noted that such parts do not necessarily correspond to the contour lines of the through holes. In particular, there is a sharp white region near the narrowed portion in the coating layer, but this is not the tip of the through hole. In both figures, the through holes have openings on the surface of the coating layer.

Table 2 below summarizes the dimensions obtained for each evaluation sample.

測定の結果から、サンプル１～サンプル３では、コーティング層内に、最小断面寸法φ_Ｑが０．６μｍ以下の狭窄部が形成されていることがわかった。

From the measurement results, it was found that in samples 1 to 3, a narrowed portion with a minimum cross-sectional dimension φ _Q of 0.6 μm or less was formed in the coating layer.

It was also found that the ratio φ _Q /φ _P of samples 1 to 3 was 0.5 or less.

100 first filter 110 body 112 first surface of body 114 second surface of body 120 inspection region 122 through hole 125 first opening 127 second opening 132a substrate through hole 132b coating layer through hole 140 substrate 142 First surface of substrate 144 Second surface of substrate 148 Substrate constriction 150 Coating layer 152 Coating layer surface 154 Constriction 220 Absorber 226a First opening 226b Second opening 240c Third opening

Claims (18)

A filter for capturing fine particles,
a transparent body having a first surface and a second surface and having a thickness of 50 μm or more;
a plurality of through holes penetrating from the first surface to the second surface of the body;
has
A _position with a depth of 10 μm from the second surface is defined as a reference depth DS,
In each through-hole, when the minimum cross-sectional dimension at the reference depth D _S is φ _P and the minimum cross-sectional dimension between the reference depth D _S and the second surface is φ _Q ,
A filter for trapping fine particles, wherein φ _Q ≤ 0.6 μm and φ _Q /φ _P ≤ 0.5. 2. The particulate filter according to claim 1, wherein _φQ is 0.2 μm or more. 3. The fine particle trapping filter according to claim 1, wherein, in each through-hole, 5 μm≦φ ₁ ≦50 μm, where φ ₁ is the minimum cross-sectional dimension of the first surface. In each through-hole, when the minimum cross-sectional dimension on the _second surface is φ2,
4. The particulate filter according to claim 1, wherein 0.2 μm≦φ ₂ ≦5 μm. 5. The particulate trapping filter according to any one of claims 1 to 4, wherein said through-hole _{monotonically} decreases in minimum cross-sectional dimension from said first surface to said reference depth DS. The particulate trapping filter according to any one of claims 1 to 5, wherein the position where the minimum cross-sectional dimension _φQ is obtained has a depth from the second surface of 0 or more and less than 5 µm. . The particulate trapping filter has an inspection area,
The particulate trapping filter according to any one of claims 1 to 6, wherein 100/ ^mm2 or more of said through-holes are provided in said inspection area. the body has a substrate and a coating layer;
The particulate filter according to any one of claims 1 to 7, wherein the second surface is the surface of the coating layer. 9. The particulate filter according to claim 8, wherein said base material is made of glass or resin. 10. The particulate filter according to claim 8, wherein said coating layer has a thickness ranging from 1 μm to 5 μm. A method for manufacturing a filter for capturing fine particles,
(I) providing a transparent substrate having first and second surfaces facing each other;
(II) irradiating the first surface of the substrate with a laser beam to form a plurality of substrate through-holes penetrating the substrate from the first surface to the second surface;
(III) placing a coating layer on the second surface of the substrate to form a plurality of through-holes penetrating the substrate and the coating layer;
A manufacturing method. Before the step (II),
12. The manufacturing method according to claim 11, comprising the step of providing an absorbent layer on said first surface of said substrate. After the step (II),
13. The manufacturing method according to claim 11 or 12, comprising the step of wet etching the base material. The manufacturing method according to any one of claims 11 to 13, wherein the substrate through-holes are arranged at a density of 100/ ^mm2 or more. The position at which the depth from the surface of the coating layer is 10 μm is defined as a reference depth _DS ,
In each through-hole, the minimum cross _- sectional dimension at the reference depth DS is _φP , the minimum cross _- sectional dimension at the surface of the coating layer is φ2, and the distance between the reference depth _DS and the surface of the coating layer is When φ _Q is the minimum cross-sectional dimension between
15. The manufacturing method according to any one of claims 11 to 14, wherein φ _Q ≤ 0.6 µm and φ _Q /φ _P ≤ 0.5. The manufacturing method according to any one of claims 11 to 15, wherein the base material has a thickness of 50 µm or more. 17. The manufacturing method according to any one of claims 11 to 16, wherein the base material is made of glass or resin. The manufacturing method according to any one of claims 11 to 17, wherein the coating layer has a thickness in the range of 1 µm to 5 µm.

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